Overall, a sensible calculator.

One surprise for me is how low the kids addition is. $18k (pre-tax) is hardly enough to cover the cost of a kid in SF. Even ignoring costs of additional housing, daycare costs are going to be over $25k/year.

Looking at the numbers:

* $90k single founder in SF - pretty easy to do (live with roommates); probably slightly excessive ($80k should be just fine for most folks)

* $108k founder with kids in SF - difficult. I'd put $120k as being a reasonable minimum with one (pre-k) kid.